Spindle depth control

ABSTRACT

A horizontal boring machine of the type having a traversing spindle and utilizing fluid motor means for driving the spindle with a tool to a cutting position then moving the tool into the workpiece to a preselected depth with electrical means actuated when said preset depth has been reached to cause a change in the flow of oil in the fluid motor to retract the spindle.

Unite at? States Patent Lehmkuhl 1 Mar. 27, 1973 SPINDLE DEPTH CONTROLInventor: Robert A. Lehmkuhl, Cincinnati,

Ohio

Assignee: The .Carlton Machine Tool 'Company,Cincinnati,Ohio

Filed: Feb. 17, 1971 Appl. No.: 116,154

U.S. Cl. ..408/3, 408/129, 408/9,

408/11 Int. Cl. ..B23b 47/18 Field of Search ..408/3, 8, 11,133,134

References Cited UNITED STATES PATENTS Caban et a1. ..408/3 3,475,99711/1969 Wohlfeil ..408/8 3,151,505 10/1964 Reichert et al ....408/33,021,464 2/1962 Philip ..408/3 Primary Examiner-Francis S. HusarAttorneyEdward J. Utz

[57] ABSTRACT A horizontal boring machine of the type having atraversing spindle and utilizing fluid motor means for driving thespindle with a tool to a cutting position then moving the tool into theworkpiece to a preselected depth with electrical means actuated whensaid preset depth has been reached to cause a change in the flow of oilin the fluid motor to retract the spindle.

2 Claims, 4 Drawing Figures PATENTEDHARZHHYS 3 723,01

SHEET 10F 4 Fig. 1

INVENTOR. Robert A. Lehmkuhl ATTORN EY PA'IEI'EHEHR271975 723,01

SHEET 30F 4 k I IIIII [um]! INVENTOR.

Robert A. Lehmkuhl TTORNEY Pmimnmznm 3,723,016

SHEET #UF 4 INVENTOR. Robert A. Lehmkuhl TTO R N EY SPINDLE DEPTHCONTROL My invention relates to a spindle depth control device such asis used with machine tools of the class having a spindle for carrying atool. in drilling and boring machines such as the type known in the artas drills and boring mills, it is desirable to move the spindle carryingthe tool to an operative position. It is also desirable in modern daypractice to move the spindle carrying the tool to its operative positionin the minimum amount of time. In drills and boring mills of the type.which I have just described, it is also necessary to determine thedistance into the work which the tool will penetrate once this sensingdevice which forms the basis of my invention becomes operative. It isalso desirable to predetermine the depth of the penetration of the toolinto the workpiece and such predetermined depth will be constant forcontinuous operation regardless of the position of the workpiece withreference to the tool. In other words, the surface of the workpiece withreference to the position of the spindle carrying structure and withreference to the depth to which the tool will penetrate the workpieceneed not be fixed. In order to accomplish an automatic setting of thedepth of the cut without reference to the distance between the toolcarrying member in its retracted or inoperative position and theworkpiece, l have devised a structure which eliminates the necessity ofa predetermined measurable distance between the workpiece and the toolin its inoperative position, and which only requires that a setting beplaced in the machine to predetermine the depth to which the tool willpenetrate the workpiece, measured from the surface of the workpiece.

Therefore, the tool, by using my invention, will'automatically drill ortap to a predetermined depth from the surface of the workpiece aftercontact with the workpiece.

With my invention, it is desirable that the traverse of the spindle fromits inoperative or retracted position of the workpiece be made at themaximum possible speed permitted by the strength of the tool taking intoaccount the effect of the impact of the tool on the work at its traverserate.

In a drilling operation, positive power feed to the spindle isimmediately engaged when the tool contacts the workpiece. This advancesthe spindle at a fixed but selectable feed rate. In a tapping operationan extremely large number of positive feed rates would be required totap the variety of sizes that would be expected to be done on a machineof this type. Therefore, a system for tapping that does not requirepositive feed rates has been incorporated in my invention.

With reference to predetermined settings of the depth of the feed in amachine tool of the class which we have described, it is only necessaryin my machine to make one setting for any given feed depth, regardlessof the position of the surface of the workpiece with reference to thespindle carrying member.

In general, in my invention I employ a fluid motor or a direct hydraulicspindle driving mechanism, which drives a rack pinion througha geartrain. This rack pinion drives or traverses a spindle mounted in thehead or tool carrying portion of the machine.

The fluid motor is geared directly to the spindle. The flow of oilthrough the fluid motor will cease when the spindle stops, causing adrop in pressure in a portion of the system which will cause thepressure switch to become operative .to perform electrical sensingfunctions to be described below. The electrical signal which is theresult of the operation just described has several functions, dependingwhether we are in a drilling or tapping mode. In a drilling mode itdisengages the fluid motor drive or other hydraulic drive; secondly, itengages the feed drive, and thirdly, it signals a feed measuring deviceso that the tool feeds to the proper depth. In a tapping mode it startsthe spindle rotation, secondly, it sequences the hydraulic circuit inorder to have the hydraulic traverse pressure maintained for a shortperiod of time until the tap is engaged into the workpiece and then thepressure is automatically reduced toprovide sufficient force to overcomethe frictional force of the sliding spindle with respect to itssupporting members, thirdly, it signals a feed measuring device so thatthe tool feeds to the proper depth.

The feed clutch provided on this type of machinery is hydraulicallyengaged, and the feed measuring device revolves until a predeterminedfeed depth is reached to end the feed, penetration, and then the spindleis retractedto its starting position.

I have further provided in my invention for a disengagement of the wormclutch to initiate a time cycle to allow for spindle dwell. Dwelling isthe process in drilling and boring operation whereby the tool ispermitted to remain in its final depth position for a period of timewhile rotation continues, to permit the squaring out of the hole. Whenthe tool reaches the maximum of its penetration as determined by themeasuring device, an electrical signal operates a series of hydraulicvalves which disengage the feed clutch and allows fluid to move throughthe fluid motor to cause the fluid motor to move in a direction oppositethat previously described to cause the spindle to be moved to itsretracted position. This is known as rapid retraction of the spindle, orthe rapid retraction phase of the work cycle. Normally, in my invention,the cycles can be repeated indefinitely by using positional controldevices so that the spindle is moved laterally to a new position andthen through cooperation with the measuring device is programmed topredetermine a depth position by means of tape or other preselect means,the cycle is repeated and the same depth or other depths of the tool maybe accomplished.

The principal object of my invention, therefore is to provide for thedrilling or tapping of holes in workpieces, without employment of anoperator to operate the machine, by having a device which may beautomatically positioned and which will automatically drill or tap ahole to a predetermined depth, regardless of the position of theworkpiece with relation to the spindle carrying tool and in a minimum oftime.

Another object of my invention is to provide a device which employshydraulic pressure or fluid motors whereby when a certain pressureswitch or pressure sensing device which is sensitive to the cessation ofmovement of fluid within the system causes certain electrical signals toactivate clutches and other mechanisms to become engaged or disengagedto perform the operations for which this machine is intended. It is tobe noted that these pressure sensing devices and pressure sensing gaugesare automatically predeterminedably settable so that an operator is notrequired for efficient operation of this device.

Another object of my invention is to provide for a time sequentialdisengagement of a pair of clutch members utilizing a time delay relayto cause one clutch and then the other clutch to become disengaged. Thedifference in the time between the disengagements of the two clutches isequal to the time of the dwell.

Another object of my invention is to provide for automatic means of feedengagement which become operable when the tool engages the surface ofthe workpiece so that the measuring of depth of cut is made from thissurface, thus insuring accuracy in depth. I

Another object of my invention is to provide an automatic means ofengaging feed the instant that the tool strikes the surface of theworkpiece, not at fixed distance away from this surface, as is common inother automatically cycling machines, thus insuring the minimum possibletime cycle for a given machining operation.

Another object of my invention is to provide for the movement of thespindle from its reference or retracted position to the workpiece at themaximum possible speed commensurate with the stability and strength ofthe tool along with its size. This is accomplished by the utilization ofadjustable valve mechanism whereby the flow of the fluid to or from thefluid motor may be adjusted to account for these conditions.

Another object of my invention is provision of a tapping system whichdoes not require positive feed rates for tapping operations but permitsthe tap to determine the spindle feed rate. d

A further object is to provide a pressure to the hydraulic motor tobalance the frictional forces of the sliding spindle with respect to.its supporting members during a tapping operation.

Another object of my invention is to preload the feed train mechanism toeliminate any backlash in the system to obtain smoother boring and moreaccurate depth control.

My invention involves a traversing spindle with a tool carried in saidspindle adapted to perform drilling and tapping operations. Thisinvention accomplishes the ultimate object automatically and without theinterference of or employment of manual operations and is intended to becompletely automatic in its function. The motivating force for themachinery described in my invention in this particular case is hydraulicfluid. The hydraulic fluid is caused to act in response to electricalsignals which are set in motion by various control devices well known inthe art and variously described as numerical or electronic controlmechanisms. This encompasses tape control as well as electronictubecontrol or other means of activating the hydraulic fluid in thismachine to perform its desired functions. The tool performs its functionin the art by drilling, tapping or boring into workpieces. This drillingand tapping must be to preselected depths for various sized holes Otherobjects and objects relating to details of construction and economies ofoperation will definitely appear from the detailed description tofollow. In one instance I have accomplished the objects of my inventionby the devices and means set forth in detail in the followingspecifications. My invention is clearly defined and pointed out in theappended claims and structures which are useful in carrying out myinvention are illustrated in the accompanying drawings. It is to beunderstood, however, that the devices and structures shown in thedrawings which accompany this applica tion for a patent are not limited,but that substitutes in the electrical and hydraulic art may be made andare within the contemplation of my invention. I

FIG. 1 is view in perspective of a horizontal boring machine,

FIG. 2 is detailed sectional view taken along the lines 2-2 of FIG. 1,

FIG. 3 is a schematic drawing of the spindle the feed train, thetraversing mechanism and measuring device, and

FIG. 4 is a hydraulic diagram of my invention.

In the drawings the same reference numerals refer to the same partsthroughout the several views, and the sectional view is taken looking inthe direction of the arrows at the ends of the section lines.

located at various lateral positions and at varying distances from thereference point. Means are provided for moving the spindle which carriesthe tool to the workpiece by utilizing hydraulic fluid in combinationwith a fluid motor, or by using other hydraulic means to cause thespindle to traverse to a cutting or working position in the shortestpossible time, and then by causing the tool in the'spindle to penetrateinto the workpiece to an automatically preselected depth, and then if itis desired, to permit the tool to dwell for a predetermined time at themaximum point of its penetration, and then to return to its reference orretracted position. The return of thetool to its retracted position isaccomplishedby reversing'the direction of oil flow through the fluidmotor in response to an electrical signal produced when the preset depthhas been reached.

There is a tappingsystem which does notrequire positive feed rates fortapping operations but permits' minimized by the forces exerted by thehydraulic mo- 1 tor.

Referring to the numbered parts of the drawings, reference is made toFIG. 1 in which I show a typical horizontal boring mill having a base20. The base'20 has a saddle 21 which is adapted to slide on ways 22 andis guided along surfaces 23 and 24. The saddle supports a column 25 onwhich is mounted a head 26,

which carries a spindle 27 for securing an operating tool such as 28.The head 26 is movable verticallyv on ways 29 on the column 25, by meansof screw 30. The spindle 27 may be manually operated by traverse wheel31.

Referring to FIG. 2, traverse wheel 31 is bolted through 32 to a quickreturn mechanism 33 to be described. I provide a quick return mechanismhaving a body 34 within which is carried a worm 37 which meshes withworm wheel 36. Secured to worm wheel 36 is quick return clutch jaw 38,slidable clutch jaw 39 is provided with serrations 40 which mate withserrations on clutch jaw 38. Clutch jaw 39 slides within gear 42 and isactuated by hydraulic pressure entering the system through port 41. Theslidable clutch jaw 39 is keyed to gear 42 which in turn meshes withgear 43 driving a spiral bevel gears 44 and 45.

Referringto FIG. 3, gear 45 mechanically connected with a jack shaft andpinion arrangement 50 to a spindle rack pinion 51 which feeds ortraverses the spindle 27 by moving of rack 52. In FIG. 3, I show thespindle driving gear 53 and spindle driven gear 54, actuated by atypical spindle driving gear mechanism well known in the art. Inoperation, rotation of spindle gear 54 rotates multiple feed gears infeed box 56 through feed gears 58a, 58b, 59 and 60. 56 is a typicalmulti-feed gear box whose out-put shaft drives bevel gears 57 and 58,bevel gear 58 drives worm 37 through dwell clutch 59. Feed worm 37drives feed .worm wheel 36 which in turn drives gear 42 through quickreturn clutch indicated at 38a. Gear 42 drives gear 43 which in turndrives bevel.

gears 44 and 45. The jack shaft 62'at'tached to bevel gear 45 rotatesbevel gear 50 which drives rack pinion 51 through bevel gear 63. Rackpinion gear 51 feeds spindle 27 through rack 52, according to the feedrate selected in the feed gear box mechanism 56. For rapid traversing ofthe spindle, hydraulic motor 64 drives gear 65 through an electricclutch 66. Gear 65 drives gear 66a which in turn meshes with 67, whichrotates rack pinion 51. An electronic feedback device 68 is rotated byreason of precision pinion 69 meshed with precision rack 70 which issecured to rack 52. The movement of the spindle 27 and the rack 52 ismonitored and controlled by the electronic feedback devise Referring toFIG. 4, the hydraulic pump 80 is driven by an electric motor 81.Hydraulic fluid is carried from reservoir 75 through strainer 76 to thehydraulic pump 80, and it is pumped through filter 79. The fluid passingthrough filter 79 will follow one of two points and will actuate thequick return clutch jaw 39 by means of solenoid valve 85 or the dwellclutch 59 by means of solenoid valve 86, or it will pass throughpressure reducing valves 87 and 88 which are selectable by means ofsolenoid valve 89. The fluid leaving the pressure reducing valve entersa three position solenoid valve 90 and is directed to hydraulic motor 64through flow control valves 91 and 92, depending upon the position ofthe three-way solenoid valve 90; Pressure switch 93 senses fluidpressure drop during surface sensing cycle.

In a surface sense drilling operation, clutch 66 is energized andsolenoid valve 90 is actuated to direct oil to hydraulic motor 64 whichadvances spindle 27. During the rapid advance of the spindle, quickreturn clutch 38a is disengaged. The pressure in the exhaust port ofhydraulic motor 64 is determined by the speed of the hydraulic motor andthe setting of the flow control valve 91. At the instant the toolcontacts the work the hydraulic pressure as seen by pressure switch 93located in exhaust port of hydraulic motor 64 drops due to the lack offlow in the hydraulic system. This drop in hydraulic pressure actuatespressure switch 93. Upon signal from pressure switch 93, the quickreturn clutch 38a is actuated by solenoid valve 85, the feed worm clutch59 is actuated by solenoid valve 86. The electric clutch 66 isdisengaged and solenoid valve 90 is de-energized which stops fluidmotion to hydraulic motor 64. The same signal from pressure switch 93also actuates electronic feedback device 68 to start the measuringsequence. The actuation of the above devices will cause the spindle toadvance the tool into the workpiece at a rate selected by the gear ratioin the feed box 56. As the tool reaches the preset depth it is measuredby feedback device 68. The quick return clutch 38 and feed worm clutch59 are disengaged by actuation of solenoid valves and 86 respectively.The spindle 27 is then rapid retracted by the engagement of clutch 66and the actuation of solenoid valve which introduces the flow of oil tohydraulic motor 64. The retract speed is determined by flow controlvalve 92.

In a boring operation, quick return clutch 38a is disengaged as well asworm feed clutch 59. In order to rapid advance the spindle to the work,we engage electric clutch 66 and actuate solenoid valve 90 which directsoil to hydraulic motor 64. Hydraulic motor 64 causes spindle 27 to rapidadvance by means of clutch 66, gears 65, 66a, feed rack pinion 51 andrack 52. During a boring operation the position of the spindle iscontinuously monitored by the feedback device 68. In boring, the rapidadvance distance of the spindle is determined by a dimension preset inthe control from an initial position of the spindle. This presetdimension is commonly known as the R-plane. When the spindle 27 reachesthe R-plane the control will cause the quick return clutch 38a and feedworm clutch 39 to be engaged by the actuation of solenoid valves 85 and86 respectively. At the same instant,-the direction of actuation ofsolenoid valve 90 will be reversed to apply hydraulic pressure to thehydraulic traverse motor 64, in a direction opposite to what the spindleis feeding. As the spindle reaches the proper depth as indicated byfeedback device 68, the feed worm clutch 59 is disengaged by actuationof solenoid valve 86. The disenretract in a rapid traverse mode. Thespindle will retract to its original point, at which time clutch 66becomes disengaged and solenoid valve 90 is returned to its neutralposition. It should be noted that in all boring operations, the dwelltime is not necessary and may be eliminated by the simultaneousdisengagement of both dwell clutch 59 and quick return clutch 380, atthe time the spindle reaches the programmed depth as measured byfeedback device 68.

In tapping, the quick return clutch 38a is disengaged through the entiretapping cycle. The spindle 27 is advanced from its retracted position bythe rotation of hydraulic motor 64, driving gear 65, 66a and rack pinion51 throughthe engaged electric clutch 66. The rotation of the rackpinion 51 causes rack 52 to rapid advance spindle 27. As the tap innonrotating spindle 27 contacts the work, pressure switch 93 is againactuated in a similar manner as in the surface sense drilling operationdescribed above. The actuation of pressure switch 93 actuates solenoidvalve 89 which causes pressure reducing valve 88 to reduce the pressure,as seen by hydraulic motor 64, to a level that just balances thefrictional forces created by the weight of the horizontal spindle 27 andrack 52 resting on their respective supporting members, thus the onlyaxial force on the tap is that which is necessary to have the tapadvance into and retract itself from the hole. The lead of the tap thendetermines the rateat which the spindle advances. The actuation ofpressure switch 93 also causes the spindle 27 to start to rotate as wellas signal feedback device 68 to start measuring the depth of the holefrom this point. It should be noted here that there is a short timedelay before solenoid valve 89 is actually actuated and after thespindle 27 is rotated. This time delay being sufficient to allow the tapto'be started into the hole by the higher traverse pressure determinedby pressure reducsure to be increased to the traverse pressure level.The spindle will then rapid retract to its original starting point whereelectric clutch 66 will become disengaged and solenoid valve will beactuated such to block the flow of oil to hydraulic motor 64.

Iclaim:

l. A horizontal boring machine having a head, a

column, said head slidably mounted on said column, a traversing spindlewithin said head, a boring tool carried in said spindle, means formoving the boring tool into the workpiece, comprising a rack connectedto said spindle, a hydraulic rapid traverse motor, first clutch meansfor selectively connecting said traverse motor to said rack, amechanical feed means, second clutch means for selectively connectingsaid mechani-. cal feed means to said rack, means for actuating saidsecond clutch means when said said spindle reaches a preselectedposition, means for preselecting the feed rate, and presettable meansfor reversing the fluid pressure in the hydraulic motor to counteractthe forward movement of the spindle during feeding with the mechanicalfeed.

2. The device of claim 1 where the means for reversing the fluidpressure in the hydraulic motor at a preselected point comprises adirectional valve.

1. A horizontal boring machine having a head, a column, said headslidably mounted on said column, a traversing spindle within said head,a boring tool carried in said spindle, means for moving the boring toolinto the workpiece, comprising a rack connected to said spindle, ahydraulic rapid traverse motor, first clutch means for selectivelyconnecting said traverse motor to said rack, a mechanical feed means,second clutch means for selectively connecting said mechanical feedmeans to said rack, means for actuating said second clutch means whensaid said spindle reaches a preselected position, means for preselectingthe feed rate, and presettable means for reversing the fluid pressure inthe hydraulic motor to counteract the forward movement of the spindleduring feeding with the mechanical feed.
 2. The device of claim 1 wherethe means for reversing the fluid pressure in the hydraulic motor at apreselected point comprises a directional valve.